Various charging apparatus and methods for rechargeable cells have been developed to increase battery life or decrease charge time.
One existing charge profile is a stepped constant-current (CC) charge profile, such as disclosed in Stephen D. Rose et al. U.S. Pat. No. 5,367,244, titled “Battery charging method with stepped current profile and associated charger,” to Premier Engineered Products, Inc. (herein, “Rose et al.”). In Rose et al., a constant charging current is provided to a battery. The constant charging current is reduced by a step current when the voltage of the battery equals a target voltage.
A pulsing charge profile is disclosed in Yury M. Padrazhansky et al. U.S. Pat. No. 6,366,056, titled “Battery charger for lithium based batteries,” to Enrev Corporation (herein, “Padrazhansky et al.”). In Padrazhansky et al., alternating series of charge current pulses, discharge pulses, and rest periods are provided to a battery.
A pulsing and constant voltage charge profile is disclosed in Seung-Won Lee U.S. Pat. No. 6,788,028, titled “Charging a battery using constant voltage and pulse,” to Sk Teletech Co., Ltd. (herein, “Lee”). In Lee, pulse charging is applied at a first current level until the charging pulse width is greater than a reference pulse width, then constant voltage charging is applied.